Using combined HPLC-RIA, cytokinin levels in a series of tobacco crown gall tumors, having altered morphologies as a result of transposon mutagenesis were examined. Average trans-ribosylzeatin levels in the shoot-producing tumors (tms mutants) and root-producing tumors (tmr mutants) were 1400 pmol/gm and 0.97 pmol/gm, respectively. Cytokinin/auxin ratios were highest in...